In many countries cannabis is the most widely used illicit drug. In the United States, adolescence and early adulthood are particularly critical periods for the initiation of cannabis use and the development of cannabis use disorders (CUDs). A recent survey of high school youth, for example, indicated that more than 2 out of 5 12th grade students have used cannabis. Similarly, based on findings from a recent national survey, researchers estimated that 2.4 million U.S. residents aged 12 years or older initiated cannabis during the prior year, and that during the same 12-month period about 4.3 million residents (or 1.7% of the U.S. population) either abused or were dependent on cannabis. Despite the importance of CUDs as a public health concern, important gaps in knowledge remain concerning the development and course of CUDs in the general population. To address these gaps, the proposed research will document several important features associated with the natural course of CUDs. To accomplish these research aims, an existing data set from the Oregon Adolescent Depression Project (OADP) will be analyzed. The OADP is a community-based and multi- generational longitudinal study that spans the peak period for the emergence of sustained patterns of hazardous cannabis use, from adolescence through early adulthood. The research described in this application will address several cannabis-related topics not previously addressed in prior OADP publications. Five broad areas are emphasized that integrate OADP's longitudinal and developmental features. (1) The prevalence of CUDs in the OADP sample will be reported, and hazards functions that describe the time to recovery from the initial CUDs episode, the probability of relapse, and the time to disorder recurrence will also be provided. (2) Subgroups of persons will be identified based on the developmental course of CUDs over the lifetime, and childhood risk factors and adult psychosocial outcomes associated with distinct trajectory subgroups will be reported. (3) The parental transmission of CUD risk will be evaluated and documented. (4) Childhood and adolescent psychiatric risk factors for later CUDs will be evaluated with proportional hazards functions and logistic regression approaches. (5) Proportional hazards modeling and logistic regression approaches will be used to evaluate the psychiatric outcomes of CUD episodes. Findings from this proposed research have the potential to inform theories of the epidemiology of CUDs, aid the development of screening tools to identify youth who are at risk for future CUDs, facilitate the development of targeted prevention programs and therapeutic interventions, and reduce the likelihood of relapse once beneficial behavior change has occurred.